Catheters are flexible medical instruments for use in the withdrawal and introduction of fluids to and from body cavities, ducts, and vessels. Catheters have particular application in hemodialysis procedures, in which blood is withdrawn from a blood vessel for treatment and subsequently returned to the blood vessel for circulation through a patient's body. The use of long-term chronic catheters in the treatment of patients requiring dialysis is common due to the necessity of repeated dialysis treatments.
Hemodialysis catheters with multiple lumens typically permit bi-directional fluid flow within the catheter, whereby one lumen is dedicated to the withdrawal of fluid from a vessel, and at least one other lumen is dedicated to the return of fluid to the vessel. Generally, the lumen through which fluid is withdrawn is referred to as the “aspiration” lumen, and the lumen through which fluid is returned is referred to as the “perfusion” lumen. Triple-lumen catheters may also enable the passage of other fluids including medicants in addition to the general use of dialysis. Some multiple-lumen catheters may include a side-port formed in a wall portion of the catheter.
In a hemodialysis procedure, after placement of a multiple-lumen catheter in a patient, blood is withdrawn from the patient through the aspiration lumen of the catheter and/or the side-port associated with the aspiration lumen, and is directed to a hemodialysis unit. The dialyzed blood is then returned to the patient's circulation through the perfusion lumen of the catheter and/or any side-port associated with the perfusion lumen.
Various tissue may begin to adhere to the exterior surface of the catheter after a period of time. These various tissues may impede the performance of the dialysis catheter by disrupting the flow of blood around the catheter or blocking the side-ports or distal opening in the lumens. For example, central vein stenosis and occlusion is commonly associated with placement of peripherally-inserted central venous catheters. More specifically, the trauma and inflammation related to catheter placement, such as denudation of the endothelium of the vessel surrounding the catheter, may result in microthrombi formation, intimal hyperplasia and fibrotic response which, over time, narrows the vessel significantly and can close off blood flow around the dialysis catheter. Similarly, thrombus or fibrin sheath may begin to adhere to the exterior of the catheter and eventually obscure any side-ports or distal openings.
Central vein stenosis, thrombus, and fibrin sheath adhesion around the catheter may result in flow disturbance or obstruction of the catheter ports and may affect the delivery of dialysis. Such flow disruption or obstruction diminishes the useful life of the catheter and may require more frequent removal and replacement of the catheter to restore flow. Improved catheter devices are needed to minimize the occurrence of central vein stenosis, thrombus or fibrin sheath adhesion to avoid hemodialysis access failure and other complications.